In silver halide color photographic materials, a light-sensitive layer comprising three kinds of silver halide emulsion layers which have been selectively sensitized so as to have a sensitivity to blue color, green color and red color, respectively is applied in a multilayer construction onto a support. For example, in a so-called color printing paper (hereinafter referred to as "color paper"), a red-sensitive emulsion layer, a green-sensitive emulsion layer, and a blue-sensitive emulsion layer are provided usually in the order stated, from the side from which exposure to light is carried out, and a color mixing-preventing or ultraviolet light-absorptive interlayer or protective layer is provided between the respective light-sensitive layers.
In forming color photographic images, three photographic color couplers of yellow, magenta, and cyan are incorporated in light-sensitive layers and, after exposure to light, the resulting light-sensitive material is subjected to color development processing using a so-called color developing agent. Coupling reaction between an oxidation product of an aromatic primary amine and each coupler provides a colored dye. In such a case, it is required to provide a color density as high as possible within a restricted developing time.
In recent years, it has been requested in this field that after receipt of order, prints obtained by development processing can be promptly delivered to users. Therefore, a silver halide color photographic material which can be rapidly processed and is excellent in processing stability has been desired. In addition, it is naturally requested to provide color prints at a low cost.
With color paper, since the blue-sensitive silver halide emulsion layer is provided on the nearest position to the support as described above, developing speed of the layer is slowest. Accordingly, it is most important to improve developing properties of the blue sensitive silver halide emulsion layer in order to enable rapid processing.
For the purpose of obtaining a high color density, it is ordinarily investigated to employ a coupler having a coupling rate as fast as possible, to employ a silver halide emulsion which is readily developed and provides a large amount of developed silver per unit coating amount, and/or to utilize a color developing solution having a high developing speed.
Various techniques on silver halide color photographic materials capable of being rapidly processed have hitherto been known. For instance, there are (1) a technique to make silver halide grains fine as described in Japanese Patent Application (OPI) No. 77223/76 (the term "OPI" as used herein means an "unexamined published patent application"); (2) a technique to lower silver bromide in silver halide as described in Japanese Patent Application (OPI) No. 184142/83 and Japanese Patent Publication No. 18939/81; (3) a technique of adding a 1-aryl-3-pyrazolidone having the specific structure to a silver halide photographic material as described in Japanese Patent Application (OPI) No. 64339/81 and further a technique of adding a 1-aryl-3-pyrazolidone to a silver halide color photographic material as described in Japanese Patent Application (OPI) Nos. 144547/82, 50534/83, 50535/83 and 50536/83; and (4) a technique of using a color development accelerator, for example, such as those as described in U.S. Pat. Nos. 2,950,970, 2,515,147, 2,496,903, 4,038,075 and 4,119,462, British Patents 1,430,998 and 1,455,413, Japanese Patent Application (OPI) Nos. 15831/78, 62450/80, 62451/80, 62452/80 and 62453/80, Japanese Patent Publication Nos. 12422/76 and 49728/80, etc.
However, when technique (3) or (4) is employed, although the processing time is shortened, processing stability is poor in the rapid processing and a problem of fog occurs. Also, when a low silver bromide emulsion is used in accordance with technique (2), a problem of low processing stability occurs while a rapid processing can be performed. Further, in the case of using fine grain silver halide according to technique (1), the severe disadvantage of decrease in sensitivity is accompanied, in addition to a problem of low processing stability.
Resently, a technique using emulsion grains having an average particle size of 0.20 .mu.m to 0.55 .mu.m as silver halide in the blue-sensitive emulsion layer is proposed as described in Japanese Patent Application (OPI) Nos. 38944/86, 52644/86, 80253/86, 80254/86, 97655/86, 100751/86 and 153639/86, etc. However, there is a problem of remarkable decrease in sensitivity, though improved effects on a rapid processing property and processing stability are recognized.
Moreover, it is preferred to employ a coupler having a high coupling activity for the purpose of imparting a rapid processing property. However, there is a severe problem in that fog increases remarkably as the coupling activity of coupler increases.